In display devices represented by a liquid crystal display, light emitting devices, such as, a semiconductor light emitting element and an organic electroluminescence element, photoelectric conversion devices, such as, a solar cell and a photodetector, or the like, ITO (Indium Tin Oxide), which is one of conductive oxide materials, is widely used as a light-transmitting electrode. The transmittance in a visible light region of an electrode with an ITO film formed on a glass substrate, is about 80%. On the other hand, the resistivity of ITO is about 10−4 Ω-cm, which is higher than the resistivity of a general metal material by about two orders of magnitude.
A light-transmitting metal electrode, in which an opening having a circumference length shorter than the wavelength of used light is provided in a metal thin film, is also considered. In this light-transmitting metal electrode, the reflectance loss in a metal part is reduced by making the rate of an area occupied by the metal part not more than 20%, preferably, not more than 10%. There is room for improvement in such a light-transmitting metal electrode, in order to obtain sufficient transparency in a broad wavelength range, while maintaining low electric resistance.